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Filipski KJ, Edmonds DJ, Garnsey MR, Smaltz DJ, Coffman K, Futatsugi K, Lee J, O’Neil SV, Wright A, Nason D, Gosset JR, Orozco CC, Blackler D, Fakhoury G, Gutierrez JA, Perez S, Ross T, Stock I, Tesz G, Dullea R. Design of Next-Generation DGAT2 Inhibitor PF-07202954 with Longer Predicted Half-Life. ACS Med Chem Lett 2023; 14:1427-1433. [PMID: 37849537 PMCID: PMC10577701 DOI: 10.1021/acsmedchemlett.3c00330] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/26/2023] [Indexed: 10/19/2023] Open
Abstract
Diacylglycerol O-acyltransferase 2 (DGAT2) inhibitors have been shown to lower liver triglyceride content and are being explored clinically as a treatment for non-alcoholic steatohepatitis (NASH). This work details efforts to find an extended-half-life DGAT2 inhibitor. A basic moiety was added to a known inhibitor template, and the basicity and lipophilicity were fine-tuned by the addition of electrophilic fluorines. A weakly basic profile was required to find an appropriate balance of potency, clearance, and permeability. This work culminated in the discovery of PF-07202954 (12), a weakly basic DGAT2 inhibitor that has advanced to clinical studies. This molecule displays a higher volume of distribution and longer half-life in preclinical species, in keeping with its physicochemical profile, and lowers liver triglyceride content in a Western-diet-fed rat model.
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Affiliation(s)
- Kevin J. Filipski
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - David J. Edmonds
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Michelle R. Garnsey
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Daniel J. Smaltz
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Karen Coffman
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kentaro Futatsugi
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jack Lee
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Steven V. O’Neil
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ann Wright
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Deane Nason
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - James R. Gosset
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Christine C. Orozco
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Dan Blackler
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Guila Fakhoury
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jemy A. Gutierrez
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Sylvie Perez
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Trenton Ross
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Ingrid Stock
- Pfizer
Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gregory Tesz
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Robert Dullea
- Pfizer
Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
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Dimitrova YN, Gutierrez JA, Huard K. It's ok to be outnumbered - sub-stoichiometric modulation of homomeric protein complexes. RSC Med Chem 2023; 14:22-46. [PMID: 36760737 PMCID: PMC9890894 DOI: 10.1039/d2md00212d] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022] Open
Abstract
An arsenal of molecular tools with increasingly diversified mechanisms of action is being developed by the scientific community to enable biological interrogation and pharmaceutical modulation of targets and pathways of ever increasing complexity. While most small molecules interact with the target of interest in a 1 : 1 relationship, a noteworthy number of recent examples were reported to bind in a sub-stoichiometric manner to a homomeric protein complex. This approach requires molecular understanding of the physiologically relevant protein assemblies and in-depth characterization of the compound's mechanism of action. The recent literature examples summarized here were selected to illustrate methods used to identify and characterize molecules with such mechanisms. The concept of one small molecule targeting a homomeric protein assembly is not new but the subject deserves renewed inspection in light of emerging technologies and increasingly diverse target biology, to ensure relevant in vitro systems are used and valuable compounds with potentially novel sub-stoichiometric mechanisms of action aren't overlooked.
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Affiliation(s)
| | | | - Kim Huard
- Genentech 1 DNA Way South San Francisco CA 94080 USA
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3
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Gutierrez JA, Liu W, Perez S, Xing G, Sonnenberg G, Kou K, Blatnik M, Allen R, Weng Y, Vera NB, Chidsey K, Bergman A, Somayaji V, Crowley C, Clasquin MF, Nigam A, Fulham MA, Erion DM, Ross TT, Esler WP, Magee TV, Pfefferkorn JA, Bence KK, Birnbaum MJ, Tesz GJ. Pharmacologic inhibition of ketohexokinase prevents fructose-induced metabolic dysfunction. Mol Metab 2021; 48:101196. [PMID: 33667726 PMCID: PMC8050029 DOI: 10.1016/j.molmet.2021.101196] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 02/07/2023] Open
Abstract
Objective Recent studies suggest that excess dietary fructose contributes to metabolic dysfunction by promoting insulin resistance, de novo lipogenesis (DNL), and hepatic steatosis, thereby increasing the risk of obesity, type 2 diabetes (T2D), non-alcoholic steatohepatitis (NASH), and related comorbidities. Whether this metabolic dysfunction is driven by the excess dietary calories contained in fructose or whether fructose catabolism itself is uniquely pathogenic remains controversial. We sought to test whether a small molecule inhibitor of the primary fructose metabolizing enzyme ketohexokinase (KHK) can ameliorate the metabolic effects of fructose. Methods The KHK inhibitor PF-06835919 was used to block fructose metabolism in primary hepatocytes and Sprague Dawley rats fed either a high-fructose diet (30% fructose kcal/g) or a diet reflecting the average macronutrient dietary content of an American diet (AD) (7.5% fructose kcal/g). The effects of fructose consumption and KHK inhibition on hepatic steatosis, insulin resistance, and hyperlipidemia were evaluated, along with the activation of DNL and the enzymes that regulate lipid synthesis. A metabolomic analysis was performed to confirm KHK inhibition and understand metabolite changes in response to fructose metabolism in vitro and in vivo. Additionally, the effects of administering a single ascending dose of PF-06835919 on fructose metabolism markers in healthy human study participants were assessed in a randomized placebo-controlled phase 1 study. Results Inhibition of KHK in rats prevented hyperinsulinemia and hypertriglyceridemia from fructose feeding. Supraphysiologic levels of dietary fructose were not necessary to cause metabolic dysfunction as rats fed the American diet developed hyperinsulinemia, hypertriglyceridemia, and hepatic steatosis, which were all reversed by KHK inhibition. Reversal of the metabolic effects of fructose coincided with reductions in DNL and inactivation of the lipogenic transcription factor carbohydrate response element-binding protein (ChREBP). We report that administering single oral doses of PF-06835919 was safe and well tolerated in healthy study participants and dose-dependently increased plasma fructose indicative of KHK inhibition. Conclusions Fructose consumption in rats promoted features of metabolic dysfunction seen in metabolic diseases such as T2D and NASH, including insulin resistance, hypertriglyceridemia, and hepatic steatosis, which were reversed by KHK inhibition. PF-06835919 is a potent inhibitor of fructose metabolism in rats and humans. Rats fed fructose at levels consistent with the typical American diet develop hyperinsulinemia, hyperlipidemia and steatosis. KHK inhibition reverses fructose-induced metabolic dysfunction by blocking ChREBP activation. Due to the global dietary prevalence of fructose, KHK inhibition is a potential pharmacotherapy for metabolic diseases.
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Affiliation(s)
- Jemy A Gutierrez
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Wei Liu
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Sylvie Perez
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Gang Xing
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Gabriele Sonnenberg
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Kou Kou
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Matt Blatnik
- Early Clinical Development, Pfizer Worldwide Research, Development, and Medical, Groton, CT 06340 USA
| | - Richard Allen
- Quantitative Systems Pharmacology, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Yan Weng
- Clinical Pharmacology, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Nicholas B Vera
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Kristin Chidsey
- Early Clinical Development, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Arthur Bergman
- Clinical Pharmacology, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Veena Somayaji
- Early Clinical Development, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Collin Crowley
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Michelle F Clasquin
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Anu Nigam
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Melissa A Fulham
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Derek M Erion
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Trenton T Ross
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - William P Esler
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Thomas V Magee
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Jeffrey A Pfefferkorn
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Kendra K Bence
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Morris J Birnbaum
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA
| | - Gregory J Tesz
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, MA 02139 USA.
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4
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Futatsugi K, Smith AC, Tu M, Raymer B, Ahn K, Coffey SB, Dowling MS, Fernando DP, Gutierrez JA, Huard K, Jasti J, Kalgutkar AS, Knafels JD, Pandit J, Parris KD, Perez S, Pfefferkorn JA, Price DA, Ryder T, Shavnya A, Stock IA, Tsai AS, Tesz GJ, Thuma BA, Weng Y, Wisniewska HM, Xing G, Zhou J, Magee TV. Discovery of PF-06835919: A Potent Inhibitor of Ketohexokinase (KHK) for the Treatment of Metabolic Disorders Driven by the Overconsumption of Fructose. J Med Chem 2020; 63:13546-13560. [PMID: 32910646 DOI: 10.1021/acs.jmedchem.0c00944] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Increased fructose consumption and its subsequent metabolism have been implicated in metabolic disorders such as nonalcoholic fatty liver disease and steatohepatitis (NAFLD/NASH) and insulin resistance. Ketohexokinase (KHK) converts fructose to fructose-1-phosphate (F1P) in the first step of the metabolic cascade. Herein we report the discovery of a first-in-class KHK inhibitor, PF-06835919 (8), currently in phase 2 clinical trials. The discovery of 8 was built upon our originally reported, fragment-derived lead 1 and the recognition of an alternative, rotated binding mode upon changing the ribose-pocket binding moiety from a pyrrolidinyl to an azetidinyl ring system. This new binding mode enabled efficient exploration of the vector directed at the Arg-108 residue, leading to the identification of highly potent 3-azabicyclo[3.1.0]hexane acetic acid-based KHK inhibitors by combined use of parallel medicinal chemistry and structure-based drug design.
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Affiliation(s)
- Kentaro Futatsugi
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Aaron C Smith
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Meihua Tu
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Brian Raymer
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Kay Ahn
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Steven B Coffey
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Matthew S Dowling
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Dilinie P Fernando
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jemy A Gutierrez
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Kim Huard
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jayasankar Jasti
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Amit S Kalgutkar
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - John D Knafels
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jayvardhan Pandit
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kevin D Parris
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Sylvie Perez
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jeffrey A Pfefferkorn
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - David A Price
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Tim Ryder
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Andre Shavnya
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ingrid A Stock
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Andy S Tsai
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gregory J Tesz
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Benjamin A Thuma
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Yan Weng
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Hanna M Wisniewska
- Pfizer Inc. Medicine Design, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gang Xing
- Pfizer Inc. Internal Medicine Research Unit, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jun Zhou
- Pfizer Inc. Drug Safety R&D, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Thomas V Magee
- Pfizer Inc. Medicine Design, 1 Portland Street, Cambridge, Massachusetts 02139, United States
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5
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Huard K, Ahn K, Amor P, Beebe DA, Borzilleri KA, Chrunyk BA, Coffey SB, Cong Y, Conn EL, Culp JS, Dowling MS, Gorgoglione MF, Gutierrez JA, Knafels JD, Lachapelle EA, Pandit J, Parris KD, Perez S, Pfefferkorn JA, Price DA, Raymer B, Ross TT, Shavnya A, Smith AC, Subashi TA, Tesz GJ, Thuma BA, Tu M, Weaver JD, Weng Y, Withka JM, Xing G, Magee TV. Discovery of Fragment-Derived Small Molecules for in Vivo Inhibition of Ketohexokinase (KHK). J Med Chem 2017; 60:7835-7849. [PMID: 28853885 DOI: 10.1021/acs.jmedchem.7b00947] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Increased fructose consumption and its subsequent metabolism have been implicated in hepatic steatosis, dyslipidemia, obesity, and insulin resistance in humans. Since ketohexokinase (KHK) is the principal enzyme responsible for fructose metabolism, identification of a selective KHK inhibitor may help to further elucidate the effect of KHK inhibition on these metabolic disorders. Until now, studies on KHK inhibition with small molecules have been limited due to the lack of viable in vivo pharmacological tools. Herein we report the discovery of 12, a selective KHK inhibitor with potency and properties suitable for evaluating KHK inhibition in rat models. Key structural features interacting with KHK were discovered through fragment-based screening and subsequent optimization using structure-based drug design, and parallel medicinal chemistry led to the identification of pyridine 12.
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Affiliation(s)
- Kim Huard
- Medicine Design, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Kay Ahn
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Paul Amor
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - David A Beebe
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Kris A Borzilleri
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Boris A Chrunyk
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Steven B Coffey
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Yang Cong
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Edward L Conn
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jeffrey S Culp
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Matthew S Dowling
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Matthew F Gorgoglione
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jemy A Gutierrez
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - John D Knafels
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Erik A Lachapelle
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jayvardhan Pandit
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kevin D Parris
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Sylvie Perez
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jeffrey A Pfefferkorn
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - David A Price
- Medicine Design, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Brian Raymer
- Medicine Design, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Trenton T Ross
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Andre Shavnya
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Aaron C Smith
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Timothy A Subashi
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gregory J Tesz
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Benjamin A Thuma
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Meihua Tu
- Medicine Design, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - John D Weaver
- Medicine Design, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Yan Weng
- Medicine Design, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jane M Withka
- Structural Biology and Biophysics, Pfizer Inc. , Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gang Xing
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Thomas V Magee
- Internal Medicine, Pfizer Inc. , 1 Portland Street, Cambridge, Massachusetts 02139, United States
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6
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Lawitz E, Poordad F, Gutierrez JA, Kakuda TN, Picchio G, Beets G, Vandevoorde A, Van Remoortere P, Jacquemyn B, Luo D, Ouwerkerk-Mahadevan S, Vijgen L, Van Eygen V, Beumont M. Simeprevir, daclatasvir and sofosbuvir for hepatitis C virus-infected patients with decompensated liver disease. J Viral Hepat 2017; 24:287-294. [PMID: 27878906 DOI: 10.1111/jvh.12645] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 10/04/2016] [Indexed: 01/08/2023]
Abstract
Approximately three million individuals in the United States are chronically infected with hepatitis C virus (HCV). Chronic HCV infection may lead to the development of compensated as well as decompensated liver cirrhosis. The Phase II IMPACT study was conducted in HCV genotype 1- or 4-infected cirrhotic patients with portal hypertension or decompensated liver disease and assessed for the first time the combination of the three direct-acting antivirals simeprevir, daclatasvir and sofosbuvir. Treatment-naïve or treatment-experienced adults with Child-Pugh (CP) score <7 (CP A) and evidence of portal hypertension, or CP score 7-9 (CP B), received 12 weeks of simeprevir 150 mg, daclatasvir 60 mg and sofosbuvir 400 mg, once daily. The primary efficacy endpoint was sustained virologic response 12 weeks after end of treatment (SVR12). Pharmacokinetics and safety were also assessed. Overall, 40 patients were enrolled (CP A: 19; CP B: 21). All 40 patients achieved SVR12. At week 8, the mean pharmacokinetic exposure to simeprevir, sofosbuvir, daclatasvir and GS-331007 (sofosbuvir metabolite) was 2.2-, 1.5-, 1.2- and 1.2-fold higher in patients with CP B than CP A, respectively. Grade 1/2 adverse events (AEs) occurred in 26 of 40 (65%) patients. One CP B patient had a Grade 3 AE (gastrointestinal haemorrhage), which was reported as a serious AE but not considered related to study drugs. Treatment for 12 weeks with simeprevir, daclatasvir and sofosbuvir was generally safe and well tolerated, and resulted in 100% of cirrhotic patients with portal hypertension or decompensated liver disease achieving SVR12.
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Affiliation(s)
- E Lawitz
- Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | - F Poordad
- Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | - J A Gutierrez
- Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | | | - G Picchio
- Janssen Research & Development LLC, Raritan, NJ, USA
| | - G Beets
- Janssen Pharmaceutica NV, Beerse, Belgium
| | | | | | | | - D Luo
- Janssen Research & Development LLC, Titusville, NJ, USA
| | | | - L Vijgen
- Janssen Pharmaceutica NV, Beerse, Belgium
| | | | - M Beumont
- Janssen Research & Development LLC, Beerse, Belgium
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7
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Ahn K, Boehm M, Brown MF, Calloway J, Che Y, Chen J, Fennell KF, Geoghegan KF, Gilbert AM, Gutierrez JA, Kalgutkar AS, Lanba A, Limberakis C, Magee TV, O’Doherty I, Oliver R, Pabst B, Pandit J, Parris K, Pfefferkorn JA, Rolph TP, Patel R, Schuff B, Shanmugasundaram V, Starr JT, Varghese AH, Vera NB, Vernochet C, Yan J. Discovery of a Selective Covalent Inhibitor of Lysophospholipase-like 1 (LYPLAL1) as a Tool to Evaluate the Role of this Serine Hydrolase in Metabolism. ACS Chem Biol 2016; 11:2529-40. [PMID: 27391855 DOI: 10.1021/acschembio.6b00266] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Lysophospholipase-like 1 (LYPLAL1) is an uncharacterized metabolic serine hydrolase. Human genome-wide association studies link variants of the gene encoding this enzyme to fat distribution, waist-to-hip ratio, and nonalcoholic fatty liver disease. We describe the discovery of potent and selective covalent small-molecule inhibitors of LYPLAL1 and their use to investigate its role in hepatic metabolism. In hepatocytes, selective inhibition of LYPLAL1 increased glucose production supporting the inference that LYPLAL1 is a significant actor in hepatic metabolism. The results provide an example of how a selective chemical tool can contribute to evaluating a hypothetical target for therapeutic intervention, even in the absence of complete biochemical characterization.
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Affiliation(s)
- Kay Ahn
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Markus Boehm
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Matthew F. Brown
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jessica Calloway
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Ye Che
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jinshan Chen
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kimberly F. Fennell
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kieran F. Geoghegan
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Adam M. Gilbert
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jemy A. Gutierrez
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Amit S. Kalgutkar
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Adhiraj Lanba
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Chris Limberakis
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Thomas V. Magee
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Inish O’Doherty
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Robert Oliver
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Brandon Pabst
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jayvardhan Pandit
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kevin Parris
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jeffrey A. Pfefferkorn
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Timothy P. Rolph
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Rushi Patel
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Brandon Schuff
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Veerabahu Shanmugasundaram
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jeremy T. Starr
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Alison H. Varghese
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Nicholas B. Vera
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Cecile Vernochet
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jiangli Yan
- Cardiovascular, Metabolic, and Endocrine Diseases (CVMED) Research
Unit, Pfizer Inc., 610 Main Street, Cambridge, Massachusetts 02139, United States
- Worldwide Medicinal Chemistry and §Pharmacokinetics, Dynamics, & Metabolism, Pfizer Inc., Eastern Point Road, Groton, Connecticut 06340, United States
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8
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Gutierrez JA, Lawitz EJ, Poordad F. Interferon-free, direct-acting antiviral therapy for chronic hepatitis C. J Viral Hepat 2015; 22:861-70. [PMID: 26083155 DOI: 10.1111/jvh.12422] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/11/2015] [Indexed: 12/13/2022]
Abstract
The treatment environment for chronic hepatitis C has undergone a revolution, particularly in genotype 1. Gone are interferon-based therapy and its associated tolerability challenges, inadequate response rates and numerous baseline factors that affect response to therapy. New and emerging treatment regimens employ all-oral combinations of direct-acting antiviral agents, and results of clinical trials suggest that these regimens routinely achieve cure rates >90%, even in patients who failed prior interferon-based triple therapy. In 2015, three all-oral FDA-approved regiments will be available for genotype 1 (sofosbuvir /ledipasvir, sofosbuvir/simeprevir, and paritaprevir/r/ombitasvir/dasabuvir). Furthermore, new treatment combinations appear to be more tolerable and require shorter duration of therapy. We provide an overview of the classes of direct-acting antiviral agents (DAAs), the clinical factors affecting their integration into combination therapies and recent findings from trials of such combination therapies in patients with genotype 1 HCV infection.
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Affiliation(s)
- J A Gutierrez
- The Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | - E J Lawitz
- The Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
| | - F Poordad
- The Texas Liver Institute, University of Texas Health Science Center, San Antonio, TX, USA
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9
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Gish RG, Gutierrez JA, Navarro-Cazarez N, Giang K, Adler D, Tran B, Locarnini S, Hammond R, Bowden S. A simple and inexpensive point-of-care test for hepatitis B surface antigen detection: serological and molecular evaluation. J Viral Hepat 2014; 21:905-8. [PMID: 24779356 PMCID: PMC4263238 DOI: 10.1111/jvh.12257] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 03/02/2014] [Indexed: 12/09/2022]
Abstract
Early identification of chronic hepatitis B is important for optimal disease management and prevention of transmission. Cost and lack of access to commercial hepatitis B surface antigen (HBsAg) immunoassays can compromise the effectiveness of HBV screening in resource-limited settings and among marginalized populations. High-quality point-of-care (POC) testing may improve HBV diagnosis in these situations. Currently available POC HBsAg assays are often limited in sensitivity. We evaluated the NanoSign(®) HBs POC chromatographic immunoassay for its ability to detect HBsAg of different genotypes and with substitutions in the 'a' determinant. Thirty-seven serum samples from patients with HBV infection, covering HBV genotypes A-G, were assessed for HBsAg titre with the Roche Elecsys HBsAg II quantification assay and with the POC assay. The POC assay reliably detected HBsAg at a concentration of at least 50 IU/mL for all genotypes, and at lower concentrations for some genotypes. Eight samples with substitutions in the HBV 'a' determinant were reliably detected after a 1/100 dilution. The POC strips were used to screen serum samples from 297 individuals at risk for HBV in local clinical settings (health fairs and outreach events) in parallel with commercial laboratory HBsAg testing (Quest Diagnostics EIA). POC testing was 73.7% sensitive and 97.8% specific for detection of HBsAg. Although the POC test demonstrated high sensitivity over a range of genotypes, false negatives were frequent in a clinical setting. Nevertheless, the POC assay offers advantages for testing in both developed and resource-limited countries due to its low cost (0.50$) and immediately available results.
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Affiliation(s)
- R G Gish
- Hepatitis B FoundationDoylestown, PA, USA
| | - J A Gutierrez
- Transplant Hepatology, University of Miami HospitalMiami, FL, USA
| | - N Navarro-Cazarez
- Division of Gastroenterology, University of California at San DiegoSan Diego, CA, USA
| | - K Giang
- Skaggs School of Pharmacy, University of California at San DiegoSan Diego, CA, USA
| | - D Adler
- Skaggs School of Pharmacy, University of California at San DiegoSan Diego, CA, USA
| | - B Tran
- Skaggs School of Pharmacy, University of California at San DiegoSan Diego, CA, USA
| | - S Locarnini
- Victorian Infectious Diseases Reference LaboratoryNorth Melbourne, VIC, Australia
| | - R Hammond
- Victorian Infectious Diseases Reference LaboratoryNorth Melbourne, VIC, Australia
| | - S Bowden
- Victorian Infectious Diseases Reference LaboratoryNorth Melbourne, VIC, Australia
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10
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Wyles DL, Gutierrez JA. Importance of HCV genotype 1 subtypes for drug resistance and response to therapy. J Viral Hepat 2014; 21:229-40. [PMID: 24597691 DOI: 10.1111/jvh.12230] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 12/12/2013] [Indexed: 12/11/2022]
Abstract
The treatment for patients infected with hepatitis C virus (HCV) genotype 1 has undergone major changes with the availability of direct-acting antivirals. Triple therapy, containing telaprevir or boceprevir, first-wave NS3 protease inhibitors, in combination with peginterferon and ribavirin, improved rates of sustained virologic response compared with peginterferon and ribavirin alone in patients with HCV genotype 1. However, the development of drug-resistant variants is a concern. In patients treated with telaprevir or boceprevir, different patterns of resistance are observed for the two major HCV genotype 1 subtypes, 1a and 1b. Genotype 1b is associated with a lower rate of resistant variant selection and better response to triple therapy compared with genotype 1a. Similar subtype-specific patterns have been observed for investigational direct-acting antivirals, including second-wave NS3 protease inhibitors, NS5A inhibitors and non-nucleoside NS5B inhibitors. This review explores resistance to approved and investigational direct-acting antivirals for the treatment of HCV, focusing on the differences between genotype 1a and genotype 1b. Finally, given the importance of HCV genotype 1 subtype on resistance and treatment outcomes, clinicians must also be aware of the tests currently available for genotype subtyping and their limitations.
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Affiliation(s)
- D L Wyles
- Division of Infectious Diseases, University of California, San Diego, CA, USA
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11
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Santos MVC, Paiva MG, Macedo CRDP, Petrilli AS, Azeka E, Jatene IB, Castro Junior CG, Seber A, Miachon AS, Tanaka ACS, Castro MAS, Carvalho AC, Nars CCF, Terzian CN, Santos CCL, Guerra CCS, Silva DCB, Bassi DU, Feitosa FA, Hamamoto F, Szarf G, Lederman HM, Rigon Junior HJ, Mota ICF, Perrud JÁ, Soares Junior J, Gutierrez JA, Perin JPM, Catani LH, Tsai LY, Vianna LC, Santos MJ, Ishigai MMS, Diógenes MSB, Alves MTS, Piedade MTC, Parreiras M, Cypriano M, Negrini NS, Campos Filho O, Figueiredo PA, Novaes PE, Camargo PR, Maia OS, Petrilli R, Arduini RG, Gouveia RV, Teruya SBM, Moisés VA, Morais VLL. I Diretriz Brasileira de Cardio-Oncologia Pediátrica da Sociedade Brasileira de Cardiologia. Arq Bras Cardiol 2013; 100:1-68. [DOI: 10.5935/abc.2013s005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Clinch K, Evans GB, Fröhlich RFG, Gulab SA, Gutierrez JA, Mason JM, Schramm VL, Tyler PC, Woolhouse AD. Transition state analogue inhibitors of human methylthioadenosine phosphorylase and bacterial methylthioadenosine/S-adenosylhomocysteine nucleosidase incorporating acyclic ribooxacarbenium ion mimics. Bioorg Med Chem 2012; 20:5181-7. [PMID: 22854195 DOI: 10.1016/j.bmc.2012.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 06/28/2012] [Accepted: 07/04/2012] [Indexed: 11/24/2022]
Abstract
Several acyclic hydroxy-methylthio-amines with 3-5 carbon atoms were prepared and coupled via a methylene link to 9-deazaadenine. The products were tested for inhibition against human MTAP and Escherichia coli and Neisseria meningitidis MTANs and gave K(i) values as low as 0.23 nM. These results were compared to those obtained with 1st and 2nd generation inhibitors (1S)-1-(9-deazaadenin-9-yl)-1,4-dideoxy-1,4-imino-5-methylthio-D-ribitol (MT-Immucillin-A, 3) and (3R,4S)-1-[9-deazaadenin-9-yl)methyl]3-hydroxy-4-methylthiomethylpyrrolidine (MT-DADMe-Immucillin-A, 4). The best inhibitors were found to exhibit binding affinities of approximately 2- to 4-fold those of 3 but were significantly weaker than 4. Cleavage of the 2,3 carbon-carbon bond in MT-Immucillin-A (3) gave an acyclic product (79) with a 21,500 fold loss of activity against E. coli MTAN. In another case, N-methylation of a side chain secondary amine resulted in a 250-fold loss of activity against the same enzyme [(±)-65 vs (±)-68]. The inhibition results were also contrasted with those acyclic derivatives previously prepared as inhibitors for a related enzyme, purine nucleoside phosphorylase (PNP), where some inhibitors in the latter case were found to be more potent than their cyclic counterparts.
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Affiliation(s)
- Keith Clinch
- Carbohydrate Chemistry, Industrial Research Limited, PO Box 31310, Lower Hutt 5040, New Zealand.
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13
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Cassera MB, Hazleton KZ, Merino EF, Obaldia N, Ho MC, Murkin AS, DePinto R, Gutierrez JA, Almo SC, Evans GB, Babu YS, Schramm VL. Plasmodium falciparum parasites are killed by a transition state analogue of purine nucleoside phosphorylase in a primate animal model. PLoS One 2011; 6:e26916. [PMID: 22096507 PMCID: PMC3214022 DOI: 10.1371/journal.pone.0026916] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 10/05/2011] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum causes most of the one million annual deaths from malaria. Drug resistance is widespread and novel agents against new targets are needed to support combination-therapy approaches promoted by the World Health Organization. Plasmodium species are purine auxotrophs. Blocking purine nucleoside phosphorylase (PNP) kills cultured parasites by purine starvation. DADMe-Immucillin-G (BCX4945) is a transition state analogue of human and Plasmodium PNPs, binding with picomolar affinity. Here, we test BCX4945 in Aotus primates, an animal model for Plasmodium falciparum infections. Oral administration of BCX4945 for seven days results in parasite clearance and recrudescence in otherwise lethal infections of P. falciparum in Aotus monkeys. The molecular action of BCX4945 is demonstrated in crystal structures of human and P. falciparum PNPs. Metabolite analysis demonstrates that PNP blockade inhibits purine salvage and polyamine synthesis in the parasites. The efficacy, oral availability, chemical stability, unique mechanism of action and low toxicity of BCX4945 demonstrate potential for combination therapies with this novel antimalarial agent.
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Affiliation(s)
- María B. Cassera
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Keith Z. Hazleton
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Emilio F. Merino
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Nicanor Obaldia
- Tropical Medicine Research, Malaria Drug and Vaccine Evaluation Center, Gorgas Memorial Institute of Health Studies, Panama City, Panama
| | - Meng-Chiao Ho
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Andrew S. Murkin
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
- Department of Chemistry, University at Buffalo, Buffalo, New York, United State of America
| | - Richard DePinto
- Waters Corporation, Parsippany, New Jersey, United State of America
| | - Jemy A. Gutierrez
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Steven C. Almo
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
| | - Gary B. Evans
- Carbohydrate Chemistry Group, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Yarlagadda S. Babu
- Department of Biological Sciences, BioCryst Pharmaceuticals Inc., Birmingham, Alabama, United State of America
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, United State of America
- * E-mail:
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14
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Hemeon I, Gutierrez JA, Ho MC, Schramm VL. Characterizing DNA methyltransferases with an ultrasensitive luciferase-linked continuous assay. Anal Chem 2011; 83:4996-5004. [PMID: 21545095 DOI: 10.1021/ac200816m] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DNA (cytosine-5)-methyltransferases (DNMTs) catalyze the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet) to the 5-position of cytosine residues and thereby silence transcription of regulated genes. DNMTs are important epigenetic targets. However, isolated DNMTs are weak catalysts and are difficult to assay. We report an ultrasensitive luciferase-linked continuous assay that converts the S-adenosyl-L-homocysteine product of DNA methylation to a quantifiable luminescent signal. Results with this assay are compared with the commonly used DNA labeling from [methyl-(3)H]AdoMet. A 5'-methylthioadenosine-adenosylhomocysteine nucleosidase is used to hydrolyze AdoHcy to adenine. Adenine phosphoribosyl transferase converts adenine to AMP and pyruvate orthophosphate dikinase converts AMP to ATP. Firefly luciferase gives a stable luminescent signal that results from continuous AMP recycling to ATP. This assay exhibits a broad dynamic range (0.1-1000 pmol of AdoHcy). The rapid response time permits continuous assays of DNA methylation detected by light output. The assay is suitable for high-throughput screening of chemical libraries for DNMT inhibition activity. The kinetic properties of human and bacterial CpG methyltransferases are characterized using this assay. Human catalytic domain DNMT3b activation by DNMT3L is shown to involve two distinct kinetic states that alter k(cat) but not K(m) for AdoMet. The assay is shown to be robust in the presence of high concentrations of the pyrimidine analogues 5-azacytidine and 5-azacytosine.
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Affiliation(s)
- Ivan Hemeon
- Department of Biochemistry, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, USA
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15
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Schramm VL, Gutierrez JA, Cordovano G, Basu I, Guha C, Belbin TJ, Evans GB, Tyler PC, Furneaux RH. Transition state analogues in quorum sensing and SAM recycling. ACTA ACUST UNITED AC 2010:75-6. [PMID: 18776260 DOI: 10.1093/nass/nrn038] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Transition state structures can be derived from kinetic isotope effects and computational chemistry. Molecular electrostatic potential maps of transition states serve as blueprints to guide synthesis of transition state analogue inhibitors of target enzymes. 5'- Methylthioadenosine phosphorylase (MTAP) functions in the polyamine pathway by recycling methylthioadenosine (MTA) and maintaining cellular S-adenosylmethionine (SAM). Its transition state structure was used to guide synthesis of MT-DADMe-ImmA, a picomolar inhibitor that shows anticancer effects against solid tumors. Biochemical and genomic analysis suggests that MTAP inhibition acts by altered DNA methylation and gene expression patterns. A related bacterial enzyme, 5'-methylthioadenosine nucleosidase (MTAN), functions in pathways of quorum sensing involving AI-1 and AI-2 molecules. Transition states have been solved for several bacterial MTANs and used to guide synthesis of powerful inhibitors with dissociation constants in the femtomolar to picomolar range. BuT-DADMe-ImmA blocks quorum sensing in Vibrio cholerae without changing bacterial growth rates. Transition state analogue inhibitors show promise as anticancer and antibacterial agents.
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Affiliation(s)
- Vern L Schramm
- Albert Einstein College of Medicine, Bronx, New York, NY 10805, USA.
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16
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Meyer ME, Gutierrez JA, Raushel FM, Richards NGJ. A conserved glutamate controls the commitment to acyl-adenylate formation in asparagine synthetase. Biochemistry 2010; 49:9391-401. [PMID: 20853825 PMCID: PMC2975022 DOI: 10.1021/bi1010688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Inhibitor docking studies have implicated a conserved glutamate residue (Glu-348) as a general base in the synthetase active site of the enzyme asparagine synthetase B from Escherichia coli (AS-B). We now report steady-state kinetic, isotope transfer, and positional isotope exchange experiments for a series of site-directed AS-B mutants in which Glu-348 is substituted by conservative amino acid replacements. We find that formation of the β-aspartyl-AMP intermediate, and therefore the eventual production of asparagine, is dependent on the presence of a carboxylate side chain at this position in the synthetase active site. In addition, Glu-348 may also play a role in mediating the conformational changes needed to (i) coordinate, albeit weakly, the glutaminase and synthetase activities of the enzyme and (ii) establish the structural integrity of the intramolecular tunnel along which ammonia is translocated. The importance of Glu-348 in mediating acyl-adenylate formation contrasts with the functional role of the cognate residues in β-lactam synthetase (BLS) and carbapenem synthetase (CPS) (Tyr-348 and Tyr-345, respectively), which both likely evolved from asparagine synthetase. Given the similarity of the chemistry catalyzed by AS-B, BLS, and CPS, our work highlights the difficulty of predicting the functional outcome of single site mutations on enzymes that catalyze almost identical chemical transformations.
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Affiliation(s)
- Megan E. Meyer
- Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, FL 32611
| | - Jemy A. Gutierrez
- Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, FL 32611
| | - Frank M. Raushel
- Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, TX 77843
| | - Nigel G. J. Richards
- Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, FL 32611
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17
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Longshaw AI, Adanitsch F, Gutierrez JA, Evans GB, Tyler PC, Schramm VL. Design and synthesis of potent "sulfur-free" transition state analogue inhibitors of 5'-methylthioadenosine nucleosidase and 5'-methylthioadenosine phosphorylase. J Med Chem 2010; 53:6730-46. [PMID: 20718423 DOI: 10.1021/jm100898v] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) is a dual substrate bacterial enzyme involved in S-adenosylmethionine (SAM) related quorum sensing pathways that regulates virulence in many bacterial species. MTANs from many bacteria are directly involved in the quorum sensing mechanism by regulating the synthesis of autoinducer molecules that are used by bacterial communities to communicate. In humans, 5'-methylthioadenosine phosphorylase (MTAP) is involved in polyamine biosynthesis as well as in purine and SAM salvage pathways and thus has been identified as an anticancer target. Previously we have described the synthesis and biological activity of several aza-C-nucleoside mimics with a sulfur atom at the 5' position that are potent E. coli MTAN and human MTAP inhibitors. Because of the possibility that the sulfur may affect bioavailability, we were interested in synthesizing "sulfur-free" analogues. Herein we describe the preparation of a series of "sulfur-free" transition state analogue inhibitors of E. coli MTAN and human MTAP that have low nano- to picomolar dissociation constants and are potentially novel bacterial anti-infective and anticancer drug candidates.
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Affiliation(s)
- Alistair I Longshaw
- Carbohydrate Chemistry Team, Industrial Research Limited, P.O. Box 31310, Lower Hutt, New Zealand
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Hartzfeld P, Elisevich K, Pace M, Smith B, Gutierrez JA. Characteristics and surgical outcomes for medial temporal post-traumatic epilepsy. Br J Neurosurg 2008; 22:224-30. [PMID: 18348018 DOI: 10.1080/02688690701818901] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A common post-traumatic location of epileptogenesis is the medial temporal lobe despite evidence of associated diffuse or remote cerebral injury. We undertook a review of post-traumatic medial temporal lobe epilepsy (MTLE) patients as part of an overall post-traumatic epilepsy population to assess the extent of cerebral injury sustained by this subpopulation and to establish whether surgical outcome differed from that of a non-traumatically-induced epilepsy population. A retrospective review of 57 patients operated for post-traumatic epilepsy (PTE) over a 10-year period (1993-2003) was undertaken with particular attention to those undergoing medial temporal resection. Preoperative magnetic resonance imaging (MRI) was assessed for the type and location of abnormalities. Postoperative outcomes were compared with those of patients with MTLE of non-traumatic origin operated by the same surgeon. Of the 57 patients operated, 30 cases underwent medial temporal lobe resection. The most common mechanism of injury was blunt trauma attributable to motor vehicle accidents with imaging abnormalities characterized by medial temporal sclerosis (MTS; 16 cases), T2/FLAIR hyperintensities (nine cases), periventricular gliosis (seven cases), diffuse cerebral atrophy (five cases) and focal encephalomalacia (three cases). Six patients had normal MRI studies. No significant differences in postoperative outcomes were found between post- and non-traumatic MTLE epilepsy groups. The presence of histopathological change in the medial temporal lobe varied greatly and provided no indication of a favourable postoperative outcome. Patients with post-traumatic medial temporal lobe epilepsy respond favourably to surgical treatment. In the case of medial temporal sclerosis, there is substantial variation of histopathological findings which correlate poorly with current imaging applications. The favourable outcomes obtained following surgery in this group attest to a commonality with other risk factors in the genesis of epilepsy in this location.
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Affiliation(s)
- P Hartzfeld
- Department of Neurosurgery, Henry Ford Health System, Detroit, Michigan 48202, USA
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19
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Gutierrez JA, Luo M, Singh V, Li L, Brown RL, Norris GE, Evans GB, Furneaux RH, Tyler PC, Painter GF, Lenz DH, Schramm VL. Picomolar inhibitors as transition-state probes of 5'-methylthioadenosine nucleosidases. ACS Chem Biol 2007; 2:725-34. [PMID: 18030989 DOI: 10.1021/cb700166z] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transition states can be predicted from an enzyme's affinity to related transition-state analogues. 5'-Methylthioadenosine nucleosidases (MTANs) are involved in bacterial quorum sensing pathways and thus are targets for antibacterial drug design. The transition-state characteristics of six MTANs are compared by analyzing dissociation constants (K(d)) with a small array of representative transition-state analogues. These inhibitors mimic early or late dissociative transition states with K(d) values in the picomolar range. Our results indicate that the K(d) ratio for mimics of early and late transition states are useful in distinguishing between these states. By this criterion, the transition states of Neisseria meningitides and Helicobacter pylori MTANs are early dissociative, whereas Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, and Klebsiella pneumoniae MTANs have late dissociative characters. This conclusion is confirmed independently by the characteristic [1'- (3)H] and [1'- (14)C] kinetic isotope effects (KIEs) of these enzymes. Large [1'- (3)H] and unity [1'- (14)C] KIEs are observed for late dissociative transition states, whereas early dissociative states showed close-to-unity [1'- (3)H] and significant [1'- (14)C] KIEs. K d values of various MTANs for individual transition-state analogues provide tentative information about transition-state structures due to varying catalytic efficiencies of enzymes. Comparing K d ratios for mimics of early and late transition states removes limitations inherent to the enzyme and provides a better predictive tool in discriminating between possible transition-state structures.
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Affiliation(s)
- Jemy A. Gutierrez
- Department of Biochemistry,
Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Minkui Luo
- Department of Biochemistry,
Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Vipender Singh
- Department of Biochemistry,
Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Lei Li
- Department of Biochemistry,
Albert Einstein College of Medicine, Bronx, New York, 10461
| | - Rosemary L. Brown
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Gillian E. Norris
- Institute of Molecular Biosciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
| | - Gary B. Evans
- Carbohydrate Chemistry Team, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Richard H. Furneaux
- Carbohydrate Chemistry Team, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Peter C. Tyler
- Carbohydrate Chemistry Team, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Gavin F. Painter
- Carbohydrate Chemistry Team, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Dirk H. Lenz
- Carbohydrate Chemistry Team, Industrial Research Ltd., Lower Hutt, New Zealand
| | - Vern L. Schramm
- Department of Biochemistry,
Albert Einstein College of Medicine, Bronx, New York, 10461
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20
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Gutierrez JA, Pan YX, Koroniak L, Hiratake J, Kilberg MS, Richards NG. An inhibitor of human asparagine synthetase suppresses proliferation of an L-asparaginase-resistant leukemia cell line. ACTA ACUST UNITED AC 2007; 13:1339-47. [PMID: 17185229 PMCID: PMC3608209 DOI: 10.1016/j.chembiol.2006.10.010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2006] [Revised: 10/05/2006] [Accepted: 10/17/2006] [Indexed: 11/17/2022]
Abstract
Drug resistance in lymphoblastic and myeloblastic leukemia cells is poorly understood, with several lines of evidence suggesting that resistance can be correlated with upregulation of human asparagine synthetase (hASNS) expression, although this hypothesis is controversial. New tools are needed to investigate this clinically important question, including potent hASNS inhibitors. In vitro experiments show an adenylated sulfoximine to be a slow-onset, tight-binding inhibitor of hASNS with nanomolar affinity. This binding affinity represents a 10-fold improvement over that reported for the only other well-characterized hASNS inhibitor. The adenylated sulfoximine has a cytostatic effect on L-asparaginase-resistant MOLT-4 cells cultured in the presence of L-asparaginase, an enzyme that depletes L-asparagine in the growth medium. These observations represent direct evidence that potent hASNS inhibitors may prove to be effective agents for the clinical treatment of acute lymphoblastic leukemia.
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Affiliation(s)
- Jemy A. Gutierrez
- Department of Chemistry, University of Florida, Gainesville, Florida 32611
| | - Yuan-Xiang Pan
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - Lukasz Koroniak
- Department of Chemistry, University of Florida, Gainesville, Florida 32611
| | - Jun Hiratake
- Institute for Chemical Research, Kyoto University, Ugi, Kyoto 611-0011, Japan
| | - Michael S. Kilberg
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
- University of Florida, Shands Cancer, Center Gainesville, Florida 32610
| | - Nigel G.J. Richards
- Department of Chemistry, University of Florida, Gainesville, Florida 32611
- University of Florida, Shands Cancer, Center Gainesville, Florida 32610
- Correspondence:
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21
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Ciustea M, Gutierrez JA, Abbatiello SE, Eyler JR, Richards NGJ. Efficient expression, purification, and characterization of C-terminally tagged, recombinant human asparagine synthetase. Arch Biochem Biophys 2005; 440:18-27. [PMID: 16023613 DOI: 10.1016/j.abb.2005.05.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 05/13/2005] [Accepted: 05/13/2005] [Indexed: 11/17/2022]
Abstract
Several lines of evidence suggest that up-regulation of asparagine synthetase (AS) in human T-cells results in metabolic changes that underpin the appearance of asparaginase-resistant forms of acute lymphoblastic leukemia (ALL). Inhibitors of human AS therefore have potential as agents for treating leukemia and tools for investigating the cellular basis of AS expression and drug-resistance. A critical problem in developing and characterizing potent inhibitors has been a lack of routine access to sufficient quantities of purified, reproducibly active human AS. We now report an efficient protocol for preparing multi-milligram quantities of C-terminally tagged, wild type human AS in a baculovirus-based expression system. The recombinant enzyme is correctly processed and exhibits high catalytic activity. Not only do these studies offer the possibility for investigating the kinetic behavior of biochemically interesting mammalian AS mutants, but such ready access to large amounts of enzyme also represents a major step in the development and characterization of inhibitors that might have clinical utility in treating asparaginase-resistant ALL.
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Affiliation(s)
- Mihai Ciustea
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
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22
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Koroniak L, Ciustea M, Gutierrez JA, Richards NGJ. Synthesis and characterization of an N-acylsulfonamide inhibitor of human asparagine synthetase. Org Lett 2003; 5:2033-6. [PMID: 12790521 DOI: 10.1021/ol034212n] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[structure: see text] The synthesis of N-acylsulfonamide 6, which is an analogue of beta-aspartyl-AMP, is described. This compound appears to be the first and only potent inhibitor of human asparagine synthetase that has been described to date. The N-acylsulfonamide 6 exhibits slow-onset inhibition kinetics, with a K(i) of 728 nM. Preparation and characterization of two additional N-acylsulfonamide analogues has also demonstrated the importance of hydrogen-bonding interactions in the recognition of the AS inhibitor with the enzyme. These observations provide the basis for the discovery of new compounds with application in the treatment of drug-resistant leukemia.
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Affiliation(s)
- Lukasz Koroniak
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA
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23
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Abstract
Currently, no published methods describe the extraction of high molecular weight genomic DNA from ixodid ticks (Acari: Ixodidae) and commonly used methods of extraction are not well adapted for use with members of this family. A method for extraction of minimally degraded genomic DNA from ixodid ticks that can be completed in one or two days is described. The method produces DNA which is of sufficient size (>24 kb) for use in Southern analysis and which is readily digestible by restriction endonucleases. Southern analysis using a cytochrome P450 gene probe, demonstrates the success of our method with genomic DNA extracted from two species of Ixodidae, the lone star tick, Amblyomma americanum (Linnaeus) and the cattle fever tick, Boophilus microplus (Canestrini).
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Affiliation(s)
- C A Hill
- Department of Biological Sciences, University of Notre Dame, PO Box 369, Notre Dame, IN 46556-0369, U.S.A.
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Gutierrez JA, Parry AJ, McMullan DM, Chapin CJ, Fineman JR. Decreased surfactant proteins in lambs with pulmonary hypertension secondary to increased blood flow. Am J Physiol Lung Cell Mol Physiol 2001; 281:L1264-70. [PMID: 11597919 DOI: 10.1152/ajplung.2001.281.5.l1264] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Infants with increased pulmonary blood flow secondary to congenital heart disease suffer from tachypnea, dyspnea, and recurrent pulmonary infections. We have recently established a model of pulmonary hypertension secondary to increased pulmonary blood flow in lambs after in utero placement of an aortopulmonary vascular graft. The purpose of the present study was to utilize our animal model to determine the effects on the expression of surfactant proteins A (SP-A), B (SP-B), and C (SP-C). At age 4 wk, SP-A mRNA content in lambs decreased to 61.4 +/- 8% of age-matched control value (n = 5; P < 0.05). In addition, SP-A protein content was decreased to 50 +/- 12% of control value (n = 6; P < 0.0001). Although we did not observe statistically significant changes in SP-B mRNA content, SP-B protein was decreased to 74 +/- 25% of control value (n = 4; P < 0.02). There was no difference in SP-C mRNA. These data show that in a model of congenital heart disease with pulmonary hypertension secondary to increased pulmonary blood flow, there is a decrease in SP-A gene expression as well as a decrease in SP-A and SP-B protein contents.
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Affiliation(s)
- J A Gutierrez
- Department of Pediatrics, University of California, San Francisco, California 94143, USA.
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25
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Abstract
Physical forces play an important role in modulating lung development, growth, compliance, differentiation and metabolism. Both tonic distension and phasic changes in volume occur during development and after birth. Morphometric studies have shown that alveolar epithelial cells are distended during lung expansion from functional residual capacity. In both in vivo and in vitro model systems, mechanical distension stimulates surfactant secretion. Drawing on the results of developmental anomalies and experiments in vivo, we and others have generated the underlying hypothesis that mechanical distension promotes expression of the type I cell phenotype and inhibits expression that of the type II; contraction has the opposite effects. The results of recent experiments, using both cultured type II cells from adult rodents and fetal lung explant tissue to test this hypothesis, provide support. The molecular and biochemical mechanisms by which physical forces affect lung functions are currently under investigation.
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Affiliation(s)
- L G Dobbs
- Cardiovascular Research Institute, University of California San Francisco: LH Campus, 3333 California Street; Suite 150, San Francisco, CA 94118, USA.
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26
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McGovern KJ, Blanchard TG, Gutierrez JA, Czinn SJ, Krakowka S, Youngman P. gamma-Glutamyltransferase is a Helicobacter pylori virulence factor but is not essential for colonization. Infect Immun 2001; 69:4168-73. [PMID: 11349094 PMCID: PMC98487 DOI: 10.1128/iai.69.6.4168-4173.2001] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The contribution of glutamyl transpeptidase (GGT) (gamma-glutamyltransferase [EC 2. 3. 2. 2]) to Helicobacter pylori virulence was investigated in piglets and mice using GGT-deficient isogenic strains. All animals became colonized. However, the bacterial load was significantly lower for mutant bacteria than for parent strains. These results suggest that GGT activity provides an advantage to H. pylori in colonization.
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Affiliation(s)
- K J McGovern
- Millennium Pharmaceuticals, Inc., Cambridge, Massachusetts, USA
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27
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Hill CA, Gutierrez JA. Analysis of the expressed genome of the lone star tick, Amblyomma americanum (Acari: Ixodidae) using an expressed sequence tag approach. Microb Comp Genomics 2001; 5:89-101. [PMID: 11087176 DOI: 10.1089/10906590050179774] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An expressed sequence tag (EST) approach was used to study the genome of two developmental stages of the lone star tick, Amblyomma americanum. cDNA libraries were constructed from the larval and adult stages of A. americanum. In total, 1942 ESTs were sequenced (1462 adult ESTs and 480 larval ESTs) and analyzed using bioinformatic programs. Contig assembly using the CAPII program revealed 11% and 15% redundancy of sequences in the larval and adult ESTs, respectively. Of the 1942 ESTs, 1738 sequences were considered quality sequences and of these, 771 or approximately 44.4% of the sequences were putatively identified based on amino acid identity using the protein Basic Local Alignment Search Tool (BLAST) algorithm. Putatively identified sequences were classified according to their predicted gene function. In total, 967 sequences, or 55.6% of the quality sequences, had limited or no protein similarity to previously identified gene products. Sequences lacking protein homology were analyzed using an automated sequence annotation system for predicted protein characteristics such as open reading frames, signal peptides, protein motifs, and transmembrane regions. In this paper we describe the sequencing of the largest number of ESTs obtained from an arachnid species to date and the subsequent detailed analysis of these sequences.
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Affiliation(s)
- C A Hill
- Elanco Animal Health, A Division of Eli Lilly and Company, Greenfield, Indiana 46140, USA.
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28
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Menon PM, Gutierrez JA, Rempel SA. A study of SPARC and vitronectin localization and expression in pediatric and adult gliomas: high SPARC secretion correlates with decreased migration on vitronectin. Int J Oncol 2000; 17:683-93. [PMID: 10995878 DOI: 10.3892/ijo.17.4.683] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SPARC is a secreted glycoprotein that interacts with extracellular matrix (ECM) proteins to promote de-adhesion of cells from the matrix, thereby inducing a biological state conducive to cell migration. We have demonstrated that SPARC is highly expressed in gliomas (grades II-IV) and promotes glioma invasion in vitro. Therefore, the protein itself or its mechanisms of action might become therapeutic targets to arrest glioma invasion. Vitronectin is an ECM protein found in the blood vessel basement membranes and may promote glioma invasion along these structures. It binds to SPARC in vitro. However, it is not known whether SPARC and vitronectin colocalize and/or interact to contribute to brain tumor cell migration in vivo. In this study, we immuno-histochemically determined if the grade I juvenile pilocytic astrocytomas (JPAs) also express SPARC, if vitronectin is expressed in grades I, II, and IV astrocytomas, and if the proteins colocalize in brain tumors in vivo. We performed western blot analyses to determine if different grades of tumors had different intracellular and/or secreted levels of SPARC and vitronectin. We performed migration assays to determine whether vitronectin is a permissive substrate for glioma migration, and whether the extent of migration correlates with the level of secreted SPARC. Our data demonstrated that JPAs expressed SPARC and secreted significantly higher levels than glioblastomas multiforme (GBMs). Vitronectin was absent from well-preserved tumor but present in areas of disrupted tumor, such as degeneration and/or necrosis. SPARC and vitronectin colocalized only in regions of angiogenesis. We observed that the extent of migration on vitronectin inversely correlated with the level of secreted SPARC: the higher the level, the lesser the migration. These data suggest that the outcome of SPARC - ECM interactions may depend on local SPARC concentrations. The high levels of SPARC secreted by the JPAs, paradoxically, may be more prohibitive for migration on vitronectin than the lower levels secreted by the GBMs. This may account, in part, for the lack of JPA invasion into brain tissue along blood vessel membranes.
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Affiliation(s)
- P M Menon
- Molecular Neuro-Oncology Laboratory, Hermelin Brain Tumor Center, Detroit, MI 48202, USA
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29
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Haider S, Nafziger D, Gutierrez JA, Brar I, Mateo N, Fogle J. Progressive multifocal leukoencephalopathy and idiopathic CD4+lymphocytopenia: a case report and review of reported cases. Clin Infect Dis 2000; 31:E20-2. [PMID: 11049808 DOI: 10.1086/318120] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Progressive multifocal leukoencephalopathy (PML) is a well recognized demyelinating neurological disorder caused by JC virus. Idiopathic CD4(+) lymphocytopenia (ICL) is a syndrome first described by the Centers for Disease Control and Prevention as a CD4(+) count <300 cells/mm(3) or a CD4(+) count that is <20% of the total T cell count on 2 occasions, with no evidence of human immunodeficiency virus (HIV) infection on testing, and absence of any defined immunodeficiency or therapy that depresses the levels of CD4(+) T cells. To the best of our knowledge, this is the third reported case of PML and ICL, and also the first reported case of the use of cidofovir to treat PML in a patient not infected with human immunodeficiency virus.
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Affiliation(s)
- S Haider
- Division of Infectious Diseases, Henry Ford Hospital, Detroit, MI 48202, USA.
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Gutmann DH, Donahoe J, Perry A, Lemke N, Gorse K, Kittiniyom K, Rempel SA, Gutierrez JA, Newsham IF. Loss of DAL-1, a protein 4.1-related tumor suppressor, is an important early event in the pathogenesis of meningiomas. Hum Mol Genet 2000; 9:1495-500. [PMID: 10888600 DOI: 10.1093/hmg/9.10.1495] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Meningiomas are common nervous system tumors, whose molecular pathogenesis is poorly understood. To date, the most frequent genetic alteration detected in these tumors is loss of heterozygosity (LOH) on chromosome 22q. This finding led to the identification of the neurofibromatosis 2 (NF2) tumor suppressor gene on 22q12, which is inactivated in 40% of sporadic meningiomas. The NF2 gene product, merlin (or schwannomin), is a member of the protein 4.1 family of membrane-associated proteins, which also includes ezrin, radixin and moesin. Recently, we identified another protein 4.1 gene, DAL-1 (differentially expressed in adenocarcinoma of the lung) located on chromosome 18p11.3, which is lost in approximately 60% of non-small cell lung carcinomas, and exhibits growth-suppressing properties in lung cancer cell lines. Given the homology between DAL-1 and NF2 and the identification of significant LOH in the region of DAL-1 in lung, breast and brain tumors, we investigated the possibility that loss of expression of DAL-1 was important for meningioma development. In this report, we demonstrate DAL-1 loss in 60% of sporadic meningiomas using LOH, RT-PCR, western blot and immunohistochemistry analyses. Analogous to merlin, we show that DAL-1 loss is an early event in meningioma tumorigenesis, suggesting that these two protein 4.1 family members are critical growth regulators in the pathogenesis of meningiomas. Furthermore, our work supports the emerging notion that membrane-associated alterations are important in the early stages of neoplastic transformation and the study of such alterations may elucidate the mechanism of tumorigenesis shared by other tumor types.
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Affiliation(s)
- D H Gutmann
- Departments of Neurology and Neuropathology, Washington University School of Medicine, St Louis, MO 63110, USA.
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Abstract
The advent of rapid DNA sequencing technologies is generating vast quantities of raw genomic information ranging from in-depth analysis of the expressed genes to complete sequencing of genomes at an increasing rate (bioinformatics). However, it is the functional characterisation of a specific gene product that is the key limiting factor for validation as targets for high throughput assay development. The challenge is to obtain the raw genomic information from parasites of economic importance and to effectively integrate broad technologies such as gene disruption and over-expression, DNA arrays, proteomics, antisense RNAs, with bioinformatics in a timely fashion to identify relevant biological targets. Screening of validated targets in a strategy that includes large numbers of chemistries with high diversity and predictive in vitro and in vivo assays should permit the successful identification of novel chemical entities with high specificity to the target parasite. It is proposed that this rational approach will permit the identification of new antiparasitic therapies able to surpass the current toxicological, environmental, and economic challenges of the marketplace.
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Affiliation(s)
- J A Gutierrez
- Elanco Animal Health. A division of Eli Lilly and Company, P.O. Box 708, Greenfield, IN 46140, USA.
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32
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Cvitkovitch DG, Gutierrez JA, Behari J, Youngman PJ, Wetz JE, Crowley PJ, Hillman JD, Brady LJ, Bleiweis AS. Tn917-lac mutagenesis of Streptococcus mutans to identify environmentally regulated genes. FEMS Microbiol Lett 2000; 182:149-54. [PMID: 10612747 DOI: 10.1111/j.1574-6968.2000.tb08889.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Previously, we demonstrated successful Tn917 mutagenesis of the oral pathogen Streptococcus mutans using pTV1-OK (Km(r), repATs), a temperature conditional replicative delivery vector carrying a lactococcal pWVO1Ts backbone. In this report we describe the construction and utilization of pTV32-OK, a plasmid harboring Tn917-lac (em(r), beta-gal(+)) that was employed to isolate transcriptional fusions of the Escherichia coli lacZ reporter gene with streptococcal promoters in S. mutans strain NG8. Tn917-lac transposition occurred at a frequency of ca. 10(-6) with 20% of the resultant em(r) clones displaying varying levels of lacZ expression. Tn917-lac mutants that expressed beta-galactosidase activity under growth conditions of glucose limitation, acidic pH, 35 mM NaCl, and elevated (42 degrees C) temperature were isolated. Further characterization of one of the mutants with increased beta-gal activity under glucose limitation, strain AS42, revealed maximal activity in batch culture in stationary phase after glucose depletion. The beta-gal activity of AS42 also was found to be repressed 3-fold in medium containing 2% glucose relative to measured activity from cells suspended in the same medium containing no glucose. Further phenotypic analysis revealed that AS42 had a 30% lower growth yield than the parent strain NG8 when grown in pH 5 medium. Sequence analysis of the region harboring the transposon revealed that the lacZ fusion occurred near the 3'-end of a gene encoding a homolog of an ATP binding protein from a family of Gram-positive ABC transporters. These findings demonstrate that Tn917-lac mutagenesis can be used to identify environmentally regulated genes in S. mutans and possibly in other medically relevant streptococcal species.
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Affiliation(s)
- D G Cvitkovitch
- University of Toronto Dental Research Institute, 124 Edward St., Toronto, Ont., Canada.
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Abstract
PURPOSE Fractionated radiosurgery is being carried out in the clinic to improve the therapeutic ratio of single-dose radiosurgery using various fractionation schemes. Because there is a paucity of experimental radiobiological data in the literature on the tumor response and late-responding normal tissue of critical intracranial structures to radiosurgery, the present animal study was designed to compare the response following a single high dose of radiation with that obtained from calculated fractionated doses of radiosurgery. METHODS AND MATERIALS Male Fischer rats with 9L gliosarcoma growing in their brains were stereotactically irradiated and assayed for the tumor control rate and brain tissue damage. The radiation dose needed for 50% tumor control (TCD50) was used as the endpoint of the efficacy of radiosurgery. Normal brain damage was measured histologically following a period of time over 270 days. Histological evaluation included hematoxylin-eosin (H & E), Luxol fast blue and periodic acid Schiff (LFB/PAS) for the presence of myelin and glial fibrillary acidic protein (GFAP) for the assessment of astrocytic re-activity. The optical density of optic nerves and chiasms staining with LFB/PAS was quantitatively measured using a computer image analysis to assess the magnitude of demyelination. RESULTS Radiosurgery (RS) was found to be more effective in curing small tumors than large tumors. The dose required to control 50% of the tumored animals for 120 days was 24, 31, and 40 Gy for 2-, 6-, and 12-day-old tumors, respectively. Using 12-day-old brain tumors, two fractions of 23.5 Gy and three fractions of 18.5 Gy were found to be equivalent to the single dose of 35 Gy for tumor control. For normal brain damages, the visual pathways including optic nerves and chiasm were found to be highly radiosensitive structures. A single dose of 35 Gy produced 100% severe optic neuropathy. The fractionated RS regimens spared substantial optic nerve damage. CONCLUSION The present data provide a strong radiobiological rationale for the use of fractionated RS in the treatment of tumors located near critical normal structures, including visual pathways. The sparing effect of fractionated RS is greater for late-responding tissues, relative to the rapidly proliferating tumor tissues. This report also characterizes the dose/time tolerance relationship of optic neuropathy after single and fractionated RS.
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Affiliation(s)
- J H Kim
- Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI 48202, USA
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Affiliation(s)
- L L Barton
- Department of Pediatrics and the Steele Memorial Children's Research Center, University of Arizona, Tucson, USA.
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Gutierrez JA, Perr HA. Mechanical stretch modulates TGF-beta1 and alpha1(I) collagen expression in fetal human intestinal smooth muscle cells. Am J Physiol 1999; 277:G1074-80. [PMID: 10564114 DOI: 10.1152/ajpgi.1999.277.5.g1074] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Intestinal muscle undergoes stretch intermittently during peristalsis and persistently proximal to obstruction. The influence of this pervasive biomechanical force on developing smooth muscle cell function remains unknown. We adapted a novel in vitro system to study whether stretch modulates transforming growth factor-beta1 (TGF-beta1) and type I collagen protein and component alpha1 chain [alpha1(I) collagen] expression in fetal human intestinal smooth muscle cells. Primary confluent cells at 20-wk gestation, cultured on flexible silicone membranes, were subjected to two brief stretches or to 18 h tonic stretch. Nonstretched cultures served as controls. TGF-beta1 protein was measured by ELISA and type I collagen protein was assayed by Western blot. TGF-beta1 and alpha1(I) collagen mRNA abundance was determined by Northern blot analysis, quantitated by phosphorimaging, and normalized to 18S rRNA. Transcription was examined by nuclear run-on assay. Tonic stretch increased TGF-beta1 protein 40%, type I collagen protein 100%, TGF-beta1 mRNA content 2.16-fold, and alpha1(I) collagen mRNA 3.80-fold and enhanced transcription of TGF-beta1 and alpha1(I) collagen by 3.1- and 4.25-fold, respectively. Brief stretch stimulated a 50% increase in TGF-beta1 mRNA content but no change in alpha1(I) collagen. Neutralizing anti-TGF-beta1 ablated stretch-mediated effects on alpha1(I) collagen. Therefore, stretch upregulates transcription for TGF-beta1, which stimulates alpha1(I) collagen gene expression in smooth muscle from developing gut.
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Affiliation(s)
- J A Gutierrez
- Department of Pediatrics, University of California, San Francisco, San Francisco, California 94143, USA
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Gutierrez JA, Ertsey R, Scavo LM, Collins E, Dobbs LG. Mechanical distention modulates alveolar epithelial cell phenotypic expression by transcriptional regulation. Am J Respir Cell Mol Biol 1999; 21:223-9. [PMID: 10423405 DOI: 10.1165/ajrcmb.21.2.3665] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The development of a normal pulmonary alveolar epithelium, essential for gas exchange, is critical for the successful adaptation to extrauterine life. From observations of natural and experimental developmental abnormalities, it has been hypothesized that mechanical factors may play a role in regulating differentiation of the pulmonary alveolar epithelium. To test this hypothesis directly, we have investigated the in vitro effects of mechanical distention on the expression of specific markers for the type I and type II cell phenotypes. Fetal rat lung (18-d) explants were mechanically distended in culture for 18 h. Mechanical distention caused an increase in RTI 40 messenger RNA (mRNA), a marker of the type I cell phenotype, of 10.6 times (n = 3, P < 0.05) that of undistended controls. In contrast, mechanical distention resulted in a decrease in mRNA content of two markers of the type II cell phenotype, surfactant protein (SP)-B and SP-C. SP-B was reduced to 10 +/- 9% (n = 3, P < 0.005) and of SP-C to 12 +/- 7% (n = 3, P < 0.0001) of undistended controls. Mechanical distention had no effect on content of mRNA for SP-A or 18S ribosomal RNA. Examined by nuclear run-on assays, mechanical distention caused changes in transcriptional rates of RTI 40, SP-B, and SP-C. These data show that mechanical distention stimulates expression of a type I cell marker and inhibits expression of markers for the type II phenotype; these effects occur at least in part at the transcriptional level. These studies support the hypothesis that mechanical distention of fetal lung tissue stimulates expression of the type I cell phenotype and inhibits expression of the type II phenotype.
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Affiliation(s)
- J A Gutierrez
- Departments of Pediatrics and Medicine and the Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA
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Malik G, Abdulrauf S, Yang XY, Gutierrez JA, Rempel SA. Expression of transforming growth factor-beta complex in arteriovenous malformations. Neurol Med Chir (Tokyo) 1999; 38 Suppl:161-4. [PMID: 10235000 DOI: 10.2176/nmc.38.suppl_161] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The factors responsible for the development of cerebral arteriovenous malformations (AVMs) are not well known. Patients with hereditary hemorrhagic telangiectasia (HHT) have cutaneous vascular dysplasia and a high propensity to develop systemic and cerebral AVMs. Transforming growth factor-beta (TGF-beta) complex has been implicated in HHT. The aim of this study was to evaluate the expression of TGF-beta 1, TGF-beta 2, TGF-beta 3, and their two receptors (R1 and R2) in AVMs and in normal brain vessels. Formalin-fixed, paraffin-embedded tissues from 20 patients with cerebral AVMs (including two patients with HHT) were sequentially sectioned into 6 microns sections. Similar sections from normal brain tissue were obtained from five patients without AVMs and no intracranial pathology, who had died from unrelated causes. The normal tissue sections included large intracranial arteries, small arteries, venous sinuses, cortical veins, and brain tissue containing arterioles, capillaries, and venules. All specimens underwent immunohistochemical analyses with polyclonal antibodies to the following antigens: TGF-beta 1, TGF-beta 2, TGF-beta 3, and R1 and R2. The immunoreactivity, when present, was consistently noted in endothelial cells and in the medial smooth muscle. The intensity of vessel wall immunostaining was graded on a scale from 0 to 3. The mean staining grades of normal vessels for TGF-beta 1, TGF-beta 2, TGF-beta 3, R1, and R2 were 0.6 (range 0-1), 3, 2.8 (range 2-3), 1.6 (range 0-2), and 3, respectively, whereas the mean staining grades of AVM vessels were 0.3 (range 0-1), 0.8 (range 0-1), 0.6 (range 0-1), 1.4 (range 0-2), and 0.9 (range 0-1), respectively. The study thus demonstrated that normal brain vessels (arteries, veins, small vessels) have strong (range 2.8-3) immunostaining for TGF-beta 2, TGF-beta 3, and R2, and that the AVM nidus vessels have a paucity (range 0.8-0.9) of staining for these factors. In AVM vessels that had zero immunoreactivity to the above three factors, the vessel wall was fibrocollagenous rather than muscular. Further studies to examine the TGF-beta complex behavior in AVMs are needed.
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Affiliation(s)
- G Malik
- Department of Neurosurgery, Henry Ford Hospital, Detroit, Michigan, USA
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Abstract
OBJECTIVE To investigate the specificity of antibodies to heat-shock protein 70 (HSP70) in patients with idiopathic, progressive, bilateral sensorineural hearing loss (IPBSNHL) and Meniere disease. STUDY DESIGN Test immunoreactivity of patients' sera using recombinant human (rh) and bovine (rb) HSP70, as well as segments representing different regions of bovine HSP70 as antigen. METHODS Sera were tested by Western blotting. RESULTS Of 52 patients with IPB-SNHL, 40 sera reacted only with rbHSP70; 12 reacted with both rbHSP70 and rhHSP70. Sera from 13 patients with IPBSNHL and from 8 with Meniere disease were tested on the panel of bovine HSP70 segments. Eleven and 7 samples, respectively, reacted with amino acid segment 427-461 from the carboxy (C)-terminal region of the molecule. CONCLUSION In IPBSNHL and Meniere disease, antibodies are directed primarily against an epitope(s) within the C-terminal region of HSP70 where diversity in sequence among different species, including possible pathogens, is greatest. These findings may provide clues to the pathogenesis or specific serodiagnosis (or both) of diseases of the inner ear.
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Affiliation(s)
- D B Bloch
- Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston 02114-2696, USA
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Gutierrez JA, Yu J, Wessling-Resnick M. Characterization and chromosomal mapping of the human gene for SFT, a stimulator of Fe transport. Biochem Biophys Res Commun 1998; 253:739-42. [PMID: 9918797 DOI: 10.1006/bbrc.1998.9836] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hemochromatosis is the most common genetic disorder known in man and results in progressive tissue deposition of iron leading to cirrhosis of the liver, hepatic carcinoma, congestive heart failure, endocrinopathies, and premature death. SFT (stimulator of Fe transport) is a newly discovered transport protein that facilitates uptake of iron. Recent studies have demonstrated that although SFT expression is reciprocally regulated in response to cellular iron levels, it is aberrantly upregulated in the liver of hemochromatosis patients, indicating that enhanced SFT expression contributes to the etiology of this disease. Here we report the molecular cloning and characterization of the human gene for SFT. FISH analysis maps the SFT gene to human chromosome 10q21. PCR analysis indicates 1000 nucleotides of intervening intron sequence near the 3' end of the coding region for SFT. Based on DNA sequence analysis of the additional 5' untranslated region obtained from the genomic clone, SFT lacks known metal-regulated transcriptional or translational control elements. These studies provide the basis for future elucidation of the mechanisms that control SFT expression in order to discover how this regulation is lost in hemochromatosis.
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Affiliation(s)
- J A Gutierrez
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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Feit H, Silbergleit A, Schneider LB, Gutierrez JA, Fitoussi RP, Réyès C, Rouleau GA, Brais B, Jackson CE, Beckmann JS, Seboun E. Vocal cord and pharyngeal weakness with autosomal dominant distal myopathy: clinical description and gene localization to 5q31. Am J Hum Genet 1998; 63:1732-42. [PMID: 9837826 PMCID: PMC1377645 DOI: 10.1086/302166] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Distal myopathy refers to a heterogeneous group of disorders in which the initial manifestations are weakness and atrophy of the hands and feet. We report a family segregating an autosomal dominant distal myopathy, with multiple affected individuals in whom vocal cord and pharyngeal weakness may accompany the distal myopathy, without involvement of the ocular muscles. To our knowledge, this pedigree displays a distinct distal myopathy with the added features of pharyngeal and vocal cord dysfunction (VCPDM) that has not been previously reported. We mapped the MPD2 gene for VCPDM to chromosome 5q within a 12-cM linkage interval between markers D5S458 and D5S1972 in a large pedigree (a maximum LOD score of 12.94 at a recombination fraction of 0 for D5S393) and combined genome screening and DNA pooling successfully adapted to fluorescent markers. This technique provides for the possibility of fully automated genome scans.
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Affiliation(s)
- H Feit
- Department of Neurology, Henry Ford Hospital, Detroit, Michigan, USA
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Abstract
The effect of metabolic inhibitors on nontransferrin bound iron transport by K562 cells was investigated. Incubation with 1 microM rotenone, 10 microM antimycin, or 0.5 mM 2,4-dinitrophenol effectively reduced ATP levels by approximately 50%. Both the rate and extent of Fe+3 uptake were impaired in ATP-depleted cells, which display a reduced Vmax for uptake. K562 cell ferrireductase activity was also lowered by metabolic inhibitors, suggesting that the apparent energy requirements for transport reside in the reduction of Fe+3 to Fe+2. However, ATP depletion was found to inhibit the rate and extent of Fe+2 uptake as well. Thus, the transbilayer passage of Fe+2 and/or Fe+3 appears to be an energy-requiring process. These features possibly reflect properties of the transport mechanism associated with a recently identified K562 cell transport protein, called SFT for "Stimulator of Fe Transport," since exogenous expression of its activity is also affected by ATP depletion.
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Affiliation(s)
- J A Gutierrez
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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Olmos JM, Fernández-Ayala M, Gutierrez JA, Val JF, González-Marcías J. Superior vena cava syndrome secondary to syphilitic aneurysm of the ascending aorta in a human immunodeficiency virus-infected patient. Clin Infect Dis 1998; 27:1331-2. [PMID: 9827300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Affiliation(s)
- J M Olmos
- Departamento de Medicina Interna, Hospital Marqués de Valdecilla, Universidad de Cantabria, Santander, Spain
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Hillman JD, Novák J, Sagura E, Gutierrez JA, Brooks TA, Crowley PJ, Hess M, Azizi A, Leung K, Cvitkovitch D, Bleiweis AS. Genetic and biochemical analysis of mutacin 1140, a lantibiotic from Streptococcus mutans. Infect Immun 1998; 66:2743-9. [PMID: 9596742 PMCID: PMC108264 DOI: 10.1128/iai.66.6.2743-2749.1998] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Streptococcus mutans JH1000 and its derivatives were previously shown (J. D. Hillman, K. P. Johnson, and B. I. Yaphe, Infect. Immun. 44:141-144, 1984) to produce a low-molecular-weight, broad-spectrum bacteriocin-like inhibitory substance (BLIS). The thermosensitive vector pTV1-OK harboring Tn917 was used to isolate a BLIS-deficient mutant, DM25, and the mutated gene was recovered by shotgun cloning in Escherichia coli. Sequence analysis of insert DNA adjacent to Tn917 led to the identification of four open reading frames including two (lanA and lanB) which have substantial homology to the Staphylococcus epidermidis structural gene (epiA) and a modifying enzyme gene (epiB) for biosynthesis of the lantibiotic epidermin, respectively. Although the BLIS activity could not be recovered from broth cultures, high yields were obtained from a solid medium consisting of Todd-Hewitt broth containing 0.5% agarose that was stab inoculated with JH1140 (a spontaneous mutant of JH1000 that produces threefold-elevated amounts of activity). Agar could not substitute for agarose. Chloroform extraction of the spent medium produced a fraction which yielded two major bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The faster-migrating band was absent in chloroform extracts of the mutant, DM25. The amino acid sequence of this band was determined by Edman sequencing and mass spectroscopy. The results showed that it is a lantibiotic, which we have named mutacin 1140, and that the sequence corresponded to that deduced from the lanA sequence. We observed a number of similarities of mutacin 1140 to epidermin and an S. mutans lantibiotic, B-Ny266, but it appears to have significant differences in the positions of its thioether bridges. It also has other unique features with regard to its leader sequence and posttranslational modification. A proposed structure for mutacin 1140 is presented.
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Affiliation(s)
- J D Hillman
- Department of Oral Biology, University of Florida College of Dentistry, Gainesville, Florida 32610, USA.
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Abstract
The pulmonary alveolar epithelium is composed of two distinct types of cells, type I and type II cells, both of which are critical for normal lung function. On the basis of experiments of both nature and in vivo studies, it has been hypothesized that expression of the type I or type II phenotype is influenced by mechanical factors. We have investigated the effects of mechanical distension on the expression of specific markers for the type I and type II cell phenotypes in cultured alveolar type II cells. Rat alveolar type II cells were tonically mechanically distended in culture. Cells were analyzed for a marker for the type I phenotype (rTI40, an integral membrane protein specific for type I cells) and for markers for the type II phenotype [surfactant protein (SP) A, SP-B, and SP-C] as well as for glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Mechanical distension caused a 68 +/- 25% (n = 3) increase in mRNA content of rTI40 relative to undistended controls. In contrast, mechanical distension resulted in a decrease in mRNA content of SP-B to 35 +/- 19% (n = 3) and of SP-C to 20 +/- 6.7% (n = 3) of undistended controls. There was no effect on mRNA content of SP-A or GAPDH. The differences in mRNA content of SP-B and SP-C were found to be primarily due to changes at the transcriptional level by nuclear run-on assays. The effects on rTI40 appear to be due to posttranscriptional events. These data show that mechanical distension influences alveolar epithelial phenotypic expression in vitro, at least in part, at the transcriptional level.
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Affiliation(s)
- J A Gutierrez
- Department of Pediatrics, University of California, San Francisco 94143-0106, USA
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Gutierrez JA, Yu J, Rivera S, Wessling-Resnick M. Functional expression cloning and characterization of SFT, a stimulator of Fe transport. J Cell Biol 1997; 139:895-905. [PMID: 9362508 PMCID: PMC2139974 DOI: 10.1083/jcb.139.4.895] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/1997] [Revised: 08/28/1997] [Indexed: 02/05/2023] Open
Abstract
A stimulator of Fe transport (SFT) was identified by functional expression cloning in Xenopus oocytes. SFT-mediated transport has properties defined for transferrin-independent Fe uptake, but its cytolocalization in recycling endosomes and the observed stimulation of transferrin-bound Fe assimilation indicate a key role in intracellular Fe membrane transport as well. SFT has six predicted transmembranous domains and a functionally important RExxE motif that resembles domains involved in yeast Fe transport and Fe-binding by ferritin L-chains. The observation that SFT oligomerizes, along with other structural and mechanistic features, suggests it may be a member of either the ATP-binding cassette or cation diffusion facilitator families. The 3' untranslated region of SFT contains a translation inhibitory element and inhibition of SFT expression in Xenopus oocytes was found to be relieved by coinjection of transcripts from other defined cDNAs that are also described in this report. SFT is the first component of the mammalian Fe membrane transport machinery to be identified.
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Affiliation(s)
- J A Gutierrez
- Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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Affiliation(s)
- J H Garcia
- Department of Pathology (Neuropathology), Henry Ford Hospital, Detroit, MI 48202, USA
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Garcia JH, Liu KF, Ye ZR, Gutierrez JA. Incomplete infarct and delayed neuronal death after transient middle cerebral artery occlusion in rats. Stroke 1997; 28:2303-9; discussion 2310. [PMID: 9368580 DOI: 10.1161/01.str.28.11.2303] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE The clinical syndrome of transient ischemic attacks is accompanied in a significant percentage of patients by brain lesions or neuroimaging abnormalities whose structural counterparts have not been defined. The objective of this study was to analyze, in an experimental model of short-term (< 25 minutes) focal ischemia and long-term (< or = 28 days) reperfusion, the extent and nature of the structural abnormalities affecting neurons and glia located within the territory of the transiently occluded artery. METHODS Adult Wistar rats (n = 121) had the origin of one middle cerebral artery (MCA) occluded with a nylon monofilament for periods of 10 to 25 minutes. Experiments of transient MCA occlusion were terminated at variable periods ranging from 1 day to 4 weeks. Control experiments consisted of (1) MCA occlusion without reperfusion (n = 7) lasting 7 to 14 days and (2) sham operations (n = 2) followed by 1- to 4-day survival. After in situ fixation, brain specimens were serially sectioned and subjected to detailed morphometric evaluations utilizing light and electron microscopes. The statistical method used to evaluate the results was based on ANOVA followed by Bonferroni's corrected t test and Student's t test comparisons. RESULTS Brain lesions were not detectable in the sham-operated controls. All brains with permanent MCA occlusion (7 to 14 days) had large infarctions with abundant macrophage infiltration and early cavitation. Forty-five (37%) of the experiments involving transient MCA occlusion had no detectable brain lesions after 4 weeks. Selective neuronal necrosis was found in 76 of 121 rats (63%) with transient MCA occlusion. Neuronal necrosis always involved the striatum, and in 29% of the brains with ischemic injury, necrosis also included a short segment of the cortex. In the striatum, the length of the arterial occlusion was the main determinant of the number of necrotic neurons (20 minutes [22.6 +/- 19] is worse than 10 minutes [4.9 +/- 7]) (P < .0001). In the cortex, the length of reperfusion determined the number of necrotic neurons appearing in layer 3. Experiments with reperfusion of 4 to 7 days' duration yielded more necrotic neurons per microscopic field (2.02 +/- 3) than those lasting fewer days (0.04 +/- 0.1) (P < .05). The histological features of these lesions underwent continuous change until the end of the fourth week, at which time necrotic neurons were still visible both in the striatum and in the cortex. CONCLUSIONS Arterial occlusions of short duration (< 25 minutes) produced, in 76 of 121 experiments (63%), brain lesions characterized by selective neuronal necrosis and various glial responses (or incomplete infarction). This lesion is entirely different from the pannecrosis/cavitation typical of an infarction that appears 3 to 4 days after a prolonged arterial occlusion. Delayed neuronal necrosis, secondary to a transient arterial occlusion or increasing numbers of necrotic neurons in experiments with variable periods of reperfusion, was a response observed only at a predictable segment of the frontoparietal cortex.
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Affiliation(s)
- J H Garcia
- Department of Pathology (Neuropathology), Henry Ford Hospital, Detroit, Mich. 48202, USA
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Gutierrez JA, Clark SG, Giulumian AD, Fuchs LC. Superoxide anions contribute to impaired regulation of blood pressure by nitric oxide during the development of cardiomyopathy. J Pharmacol Exp Ther 1997; 282:1643-9. [PMID: 9316882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Basal release of endothelium-derived nitric oxide (NO) has been shown to modulate vascular tone and arterial pressure, and may be altered in disease states. The present study was designed to evaluate the role of nitric oxide synthase (NOS) in the maintenance of mean arterial pressure (MAP) and heart rate (HR) in early and advanced stages of cardiomyopathy. MAP and HR were measured via a carotid arterial cannula in conscious, unrestrained male Golden Syrian and Syrian cardiomyopathic hamsters. Studies were performed in young hamsters (age, 60-90 days) at the early phase and old hamsters (age, 300-350 days) at the advanced phase of cardiomyopathy. N-Nitro-L-arginine (LNA; 0.3-30 micromol/kg i.a.), an inhibitor of NOS activity, produced a dose-dependent increase in MAP in YC (young control) and OC (old control) hamsters. The LNA-induced increase in MAP was significantly impaired in YM (young cardiomyopathic) and was abolished in OM (old cardiomyopathic) hamsters compared with control hamsters. Bradycardia in response to LNA was similar in all groups. The effects of LNA on MAP and HR were reversed by L-arginine (200 mg/kg i.a.). Phenylephrine (0.3-300 microg/kg i.a.), an alpha adrenoceptor agonist, produced a dose-dependent increase in MAP which was similar in C and M hamsters at both ages, which indicated that impaired pressor responses to LNA were not caused by a nonspecific alteration in vascular responsiveness of M hamsters. Additionally, L-arginine (100 or 300 mg/kg i.a.), the precursor to NO and sodium nitroprusside (0.3-300 microg/kg i.a.), an NO donor, produced similar effects on MAP and HR in all groups of hamsters. Endothelial NOS protein levels in aorta isolated from each group of hamsters were similar. In the presence of tiron (1000 mg/kg), a superoxide anion scavenger, the effects of LNA on MAP were significantly restored in OM compared with OC hamsters. These results indicate that the role of NO in regulation of MAP is reduced during the development of cardiomyopathy. This effect is not the result of a deficiency of L-arginine, a reduced sensitivity to exogenous NO or a decrease in vascular endothelial NOS protein in cardiomyopathic hamsters. However, scavenging of NO by superoxide anions may contribute to the diminished role of NO in regulation of blood pressure in the advanced stage of cardiomyopathy.
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Affiliation(s)
- J A Gutierrez
- Department of Pediatrics, Medical College of Georgia, Augusta 30912, USA
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Crowley PJ, Gutierrez JA, Hillman JD, Bleiweis AS. Genetic and physiologic analysis of a formyl-tetrahydrofolate synthetase mutant of Streptococcus mutans. J Bacteriol 1997; 179:1563-72. [PMID: 9045814 PMCID: PMC178867 DOI: 10.1128/jb.179.5.1563-1572.1997] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Previously we reported that transposon Tn917 mutagenesis of Streptococcus mutans JH1005 yielded an isolate detective in its normal ability to produce a mutacin (P. J. Crowley, J. D. Hillman, and A. S. Bleiweis, abstr. D55, p. 258 in Abstracts of the 95th General Meeting of the American Society for Microbiology 1995, 1995). In this report we describe the recovery of the mutated gene by shotgun cloning. Sequence analysis of insert DNA adjacent to Tn917 revealed homology to the gene encoding formyl-tetrahydrofolate synthetase (Fhs) from both prokaryotic and eukaryotic sources. In many bacteria, Fhs catalyzes the formation of 10-formyl-tetrahydrofolate, which is used directly in purine biosynthesis and formylation of Met-tRNA and indirectly in the biosynthesis of methionine, serine, glycine, and thymine. Analysis of the fhs mutant grown anaerobically in a minimal medium demonstrated that the mutant had an absolute dependency only for adenine, although addition of methionine was necessary for normal growth. Coincidently it was discovered that the mutant was sensitive to acidic pH; it grew more slowly than the parent strain on complex medium at pH 5. Complementation of the mutant with an integration vector harboring a copy of fhs restored its ability to grow in minimal medium and at acidic pH as well as to produce mutacin. This represents the first characterization of Fhs in Streptococcus.
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Affiliation(s)
- P J Crowley
- Department of Oral Biology, University of Florida, Gainesville 32610, USA.
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50
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Abstract
In work previously reported (J. A. Gutierrez, P. J. Crowley, D. P. Brown, J. D. Hillman, P. Youngman, and A. S. Bleiweis, J. Bacteriol. 178:4166-4175, 1996), a Tn917 transposon-generated mutant of Streptococcus mutans JH1005 unable to synthesize glutamate anaerobically was isolated and the insertion point of the transposon was determined to be in the icd gene encoding isocitrate dehydrogenase (ICDH). The intact icd gene of S. mutans has now been isolated from an S. mutans genomic plasmid library by complementation of an icd mutation in Escherichia coli host strain EB106. Genetic analysis of the complementing plasmid pJG400 revealed an open reading frame (ORF) of 1,182 nucleotides which encoded an enzyme of 393 amino acids with a predicted molecular mass of 43 kDa. The nucleotide sequence contained regions of high (60 to 72%) homology with icd genes from three other bacterial species. Immediately 5' of the icd gene, we discovered an ORF of 1,119 nucleotides in length, designated citZ, encoding a homolog of known citrate synthase genes from other bacteria. This ORF encoded a predicted protein of 372 amino acids with a molecular mass of 43 kDa. Furthermore, plasmid pJG400 was also able to complement a citrate synthase (gltA) mutation of E. coli W620. The enzyme activities of both ICDH, found to be NAD+ dependent, and citrate synthase were measured in cell extracts of wild-type S. mutans and E. coli mutants harboring plasmid pJG400. The region 5' from the citZ gene also revealed a partial ORF encoding 264 carboxy-terminal amino acids of a putative aconitase gene. The genetic and biochemical evidence indicates that S. mutans possesses the enzymes required to convert acetyl coenzyme A and oxalacetate to alpha-ketoglutarate, which is necessary for the synthesis of glutamic acid. Indeed, S. mutans JH1005 was shown to assimilate ammonia as a sole source of nitrogen in minimal medium devoid of organic nitrogen sources.
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Affiliation(s)
- D G Cvitkovitch
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, USA.
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